Re: [PATCH 2/3] hwmon: Add support for SPD5118 compliant temperature sensors

[Armin Wolf]

Am 30.05.24 um 19:33 schrieb Guenter Roeck:

> On 5/30/24 10:03, Armin Wolf wrote:
> > Am 29.05.24 um 22:52 schrieb Guenter Roeck:
> [ ... ]
>
> > > +
> > > +temp1_lcrit_alarm    Temperature low critical alarm
> > > +temp1_min_alarm        Temperature low alarm
> > > +temp1_max_alarm        Temperature high alarm
> > > +temp1_crit_alarm    Temperature critical alarm
> >
> > Maybe it would be a good idea to tell users that the alarm attributes
> > are sticky.
>
> The driver auto-clears them after read, so they are only sticky in the
> sense
> that they will remain active until read. This is quite common for
> hardware
> monitoring devices. However, sure, I'll add a note.
>
> [ ... ]
>
> > > +static int spd5118_write_enable(struct regmap *regmap, u32 attr,
> > > long val)
> > > +{
> > > +    if (val && val != 1)
> > > +        return -EINVAL;
> > > +
> > > +    return regmap_update_bits(regmap, SPD5118_REG_TEMP_CONFIG,
> > > +                  SPD5118_TS_DISABLE,
> > > +                  val ? 0 : SPD5118_TS_DISABLE);
> >
> > The spd5118 spec says that we have to wait 10ms after enabling the
> > sensors before
> > we start reading temperature values, maybe we need a delay + locking
> > here?
>
> I don't think that would add much if any value but a lot of complexity
> for little gain. I find it acceptable that the sensor returns 0 for a
> few ms
> after enabling it. Pretty much all chips have the same problem, so I am
> really not concerned about it.
>
> > > +
> > > +static struct i2c_driver spd5118_driver = {
> > > +    .class        = I2C_CLASS_HWMON,
> > > +    .driver = {
> > > +        .name    = "spd5118",
> > > +        .of_match_table = spd5118_of_ids,
> >
> > The driver is missing suspend support, without it hibernation/S4
> > sleep will cause the
> > limit and config registers to be out of sync with the regmap cache.
>
> Good point. Do you have a means to test this if I add suspend support ?
> I have not been able to figure out how to put my system into suspend.
>
> Thanks,
> Guenter
I think so, at least i can verify if S3 sleep works, but S4 sleep should work fine too.

Thanks,
Armin Wolf